1. Field of the Invention
This invention relates to an improved internal combustion engine coolant system and to an improved thermostat therefor as well as to methods of making the same.
2. Prior Art Statement
It is known to provide an internal combustion engine coolant system having a radiator for receiving coolant into an inlet thereof from an outlet of the engine through a thermostat disposed intermediate the outlet of the engine and the inlet of the radiator and having a coolant pump for circulating the coolant through the engine from an inlet of the engine to the outlet thereof, the pump having a first inlet interconnected to the outlet of the engine upstream of the thermostat and a second inlet interconnected to the outlet of the radiator while having its outlet interconnected to the inlet of the engine. The thermostat has a vent valve means carried by the main valve member thereof or other part of the thermostat for venting air from the outlet of the engine to the inlet of the radiator when the main valve member of the thermostat is in a closed condition against the main valve seat thereof and the system is being filled with coolant that is being introduced into the radiator and for preventing coolant flow through the vent valve means when the pump is circulating the coolant and the main valve member of the thermostat is in a closed condition against the main valve seat.
For example, see the following three United States patents:
(1) U.S. Pat. No. 2,829,835--Branson PA1 (2) U.S. Pat. No. 3,973,729--Sliger PA1 (3) U.S. Pat. No. 4,091,991--Sliger
It appears that the valve seat structure of the thermostat of the engine coolant system of Item (1) above has a vent opening passing therethrough and in which is disposed a "jiggle" pin which permits air to be vented through the opening during a coolant filling operation but which will close the vent opening when a coolant pressure is being created by the coolant pump circulating the coolant at the same time that the thermostat is in its closed condition.
It appears that the movable valve member of the thermostat of the engine coolant system of Item (2) above carries a one-piece valve seat member that confines a movable ball valve member therein which normally maintains the valve seat in an open condition to permit air to vent through the open valve seat from the outlet of the engine to the inlet of the radiator during a coolant filling operation and thereafter moving to a closed position against the valve seat by a coolant pressure when the pump is circulating the coolant through the engine and the thermostat is in a closed condition thereof.
It appears that the vent valve means of the engine coolant system of Item (3) above comprises a small notch disposed in the thermostat which provides a leakage path from the engine side of the thermostat to the radiator so that if the engine cooling system is being filled with coolant through the radiator fill neck, the coolant will pass through the radiator, coolant pump, and the engine coolant passage means. As the coolant fills these passages, the air which the coolant displaces can readily pass through the leak notch of the closed thermostat and then finally through the radiator fill neck to the atmosphere. However, this leak notch in the thermostat does not close and provides a leakage path for the coolant to pass through the leak notch to the radiator during engine operation before the thermostat has opened.